OBJECTIVE: To investigate the feasibility and potential efficacy of 'activeTENS' (that is transcutaneous electrical nerve stimulation (TENS) during everyday activities) by assessing the immediate effects on strength, proprioception, balance/falls risk and mobility after stroke. DESIGN: A paired-sample randomized cross-over trial. SUBJECTS: Twenty-nine mobile chronic stroke survivors with no pre-existing conditions limiting balance or mobility or contra-indications to TENS. SETTING: University clinical research facility. INTERVENTION: A single session of 'activeTENS' delivered via a 'sock electrode' (70-130 Hz, five second cycle) plus a session of control treatment (wearing the sock electrode with no stimulation), lasting approximately two hours in total. MAIN OUTCOMES: Dorsiflexor and plantarflexor strength and proprioception using an isokinetic dyanometer, balance and falls risk (Standing Forward Reach Test) and gait speed (10-m walk test). RESULTS: All participants tolerated 'active TENS'. Most parameters improved during stimulation with activeTENS; balance (p = 0.009), gait speed (p = 0.002), plantarflexor strength (p = 0.008) and proprioception of plantarflexion (p = 0.029), except dorsiflexor strength (p = 0.194) and dorsiflexion proprioception (p = 0.078). CONCLUSIONS: The results provide initial evidence of the potential of 'active TENS' to benefit physical function after stroke which warrants further phase II trials to develop the intervention. Concerns that stimulation could have a detrimental impact on balance and increase risk of falls were not supported.